In lung cancer stem cells, eight differently expressed genes (Krueppel-like transcription factor 4 (KLF4), secretoglobin family 3 A member1 (SCGB3A1), collagen type I alpha 1 chain (COL1A1), secreted phosphoprotein 1 (SPP1), Complement Component 4 Binding Protein Alpha (C4BPA), Tetraspanin 7 (TSPAN7), caveolin 2 (CAV2), and Collagen Triple Helix Repeat Containing 1 (CTHRC1); stemness gene signature) were tested and validated in vitro as markers to predict the lung cancer progression [118]. The gene discussed is SPP1; the disease is lung cancer.